What would a square thing be doing down there? I suppose if they have spaceships like we have cars, then it does not matter where you live because you can always "get to the shops" by air. So living at the bottom of a crater is probably one of the safest places (since it is not likely that the same place will be hit twice with an asteroid ?) Maybe the view is beautiful to alien eyes? Possibly a minig operation and the black/dark patch above and to the right is a mine or hole into the side of the crater.

"Next summer, about exactly a year from now, Dawn will arrive at Vesta, the asteroid belt's second-largest resident. And while Vesta is technically an asteroid, it won't make a whole heck of a lot of sense to include it with this montage. To get a sense of how Vesta compares to all the things that we've visited before, here is Vesta and the same montage as above, presented at the same scale of two kilometers per pixel: "

Source: http://www.planetary.org/blog/article/00002585/

I thought I would enhance it to show a realistic view of such "asteroid"